How strange, as I am in exactly the same situation! I had a really foul smelling discharge for days, which was often brown coloured. I was really embarassed by the smell and getting a bit worried about it. I looked for a tampon, but didn't find one... until today!
When I took it out it absolutely stank- it had obviously started to rot. I searched to see if there were any health problems associated, but haven't found any. I was aware of TSS, but have felt well, so I don't consider that to be a possibility.